Romanian Campaign

The Romanian Campaign was a theatre of World War I which lasted from 27 August 1916 to December 1917. It began when Romania - inspired by the Brusilov Offensive - decided to enter the war on the Entente side, intending on conquering the Romanian cultural region of Transylvania from Austria-Hungary. However, Romania was invaded from multiple directions, as Austro-German armies invaded from the north and west and Bulgarian forces invaded from the south. In December 1917, Romania was forced to sign an armistice with the Central Powers, and it accepted punitive peace terms in May 1918.

Background
The Kingdom of Romania was an ally of Germany and Austria-Hungary before World War I, but it chose to remain neutral at the outbreak of war. Romania was connected to Germany through its royal family, who were Hohenzollerns. However, it nursed ambitions to annex Transylvania and Bukovina, territories in Austria-Hungary with a large ethnic Romanian population. Romania fought against Bulgaria in the Second Balkan War in 1913, gaining a substantial slice of Bulgarian territory. Although Romania's King Carol I was bound to the Central Powers by a secret treaty signed in 1883, popular opinion was hostile to Austria-Hungary. The king thus opted for neutrality in August 1914. Romania joined the war in summer 1916, when the success of the Brusilov Offensive opened the prospect of defeating Austria-Hungary.

Campaign
The Romanians signed a treaty with Allied negotiators in Bucharest on 17 August 1916. In return for entering the war, Romania would be allowed to annex Transylvania, Bukovina, and other territories, chiefly at the expense of Hungary. As part of the Bucharest agreement, the Allies promised military action in support of Romanian forces. Russia would renew its offensive on the Austro-Hungarian front while British, French, and other Allied forces attacked Bulgaria from their base at Salonika in northern Greece.

Romania goes to war
With these assurances, Romania declared war on the Central Powers on 27 August. The Romanian conscript army, numbering some 650,000, had an impressive reputation gained against the Bulgarians in the Second Balkan War of 1913. The troops were, however, short of equipment, with outdated rifles, few machine guns, and little artillery.

Romanian strategy focused on fulfilling its territorial ambitions. Advancing through inadequately defended mountain passes into Hungary, Romanian forces occupied eastern Transylvania. If they had done this a few months earlier, when the Russian Brusilov Offensive was succeeding, it might have conttributed to the collapse of Austria-Hungary. But by September, Russian operations were running out of steam and the Germans, under their new Chief of the General Staff Field Marshal Paul von Hindenburg, were able to intervene to shore up their Austro-Hungarian ally. Hindenburg's predecessor as Chief of the General Staff, General Erich von Falkenhayn, was sent to take overall command of operations against Romania, while also leading the German 9th Army in Transylvania.

The experienced field marshal August von Mackensen was sent to Bulgaria to command a combined force of Bulgarian and German troops on the Danube front opposite Romania's southern border. They were later joined by Turkish troops carried by ship across the Black Sea.

Problems mount
Romania's allies failed to provide their promised military support. The Russians regarded the Romanian front as a distraction, and the assistance they provided was limited and slow. Initially, just 50,000 Russian troops were sent to stiffen the Romanian army. The planned offensive from Salonika, under French general Maurice Sarrail, was preempted by German and Bulgarian attacks in southern Serbia and eastern Greece in August. Outmaneuvered, Sarrail achieved only a limited advance when he launched his offensive in September, crawling forward to face the Bulgarians out of Monastir (modern-day Bitola in Macedonia) by mid-November.

Left exposed to an invasion from Bulgaria and to counterattacks in Transylvania, Romania was soon in dire straits. Mackensen led his forces from Bulgaria into Romania's Dobruja province on 1 September. To meet the threat, the Romanians transferred 150,000 troops from Transylvania to the Danube in mid-September, and attempted an ambitious counteroffensive at the end of the month, including crossing the Danube to attack Mackensen's army from the rear.

March on Bucharest
Disrupted by adverse weather conditions, the river crossing proved a chaotic failure and was abandoned on 3 October. Falkenhayn then launched the German Ninth Army and the Austro-Hungarian 1st Army in an offensive against the Romanina forces in Transylvania, bursting through teh Vulcan Pass into Wallachia. Falkenhayn and Mackensen's armies advanced on the Romanian capital, Bucharest, from the south and west. The city fell on 6 December.

The Romanians had lost more than 300,000 men, a large proportion of them taken prisoner. The survivors retreated north into Moldavia, behind the Sereth River. British agents tried to destroy the oil installations at Ploesti, 35 miles north of Bucharest, but these fell into German hands, as did the Black Sea port of Costanza. Hampered by bad roads and winter weather, the Germand and their allies failed to mount an effective pursuit. As fighting died down for the winter elsewhere on the Eastern Front, Russia belatedly began transferring forces to Romania from the end of October. Most did not arrive until December, in time to stabilize a defensive line that left most of Romania occupied by the Central Powers.

Under occupation
Mackensen was installed as military governor of the area of Romania controlled by the Central Powers. His main task was to ensure that supplies of grain, oil, and other materials flowed to Germany. As a consequence, many Romanians suffered from malnutrition. Around half a million of them are estimated to have died of hardships and deficiencies.

Aftermath
With most of its territory occupied by the Central Powers, from the start of 1917 Romania was subjected to economic exploitation. Holding Moldavia, the Romanian army fought well alongside teh Russians, but their efforts were undermined by the failure of the Russian Kerensky Offensive. German attacks on Moldavia were repulsed, but the Bolshevik Revolution and the Russian Civil War left them isolated. After an armistice with Germany in December 1917, the Romanian government accepted punitive peace terms in May 1918. Romania nominally reentered the war on the Allied side on 10 November 1918.